Elucidation of electron-band filling and pi-d electron interaction due to randomness in strongly correlated pi-electron systems

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K05430
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Tohoku University
• Principal Investigator: Iguchi Satoshi 東北大学, 金属材料研究所, 准教授 (50431789)
• Research Collaborator: Yoneyama Naoki ; Itoh Hirotake
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: フィリング制御 / 電荷秩序 / 金属ー絶縁体転移 / πーd電子間相互作用

Outline of Final Research Achievements

a''-(BEDT-TTF)2RbCo(SCN)4 is a newly found strongly correlated π-electron system with the BEDT-TTF molecule of +0.4 valence or 0.8 π-electron band-filling due to the non stoichiometric Rb. This compound is suitable for the investigation for the filling-controll type metal-insulator transition. We have investigated the metal-insulator transition and theπ-d electron correlation of this system and other similar ones. We found that the insulator phase in the compound is a charge ordered state with 0.4 average valence of BEDT-TTF molecules, and phase transition by pressure from metal to semiconductor even at room temperature.

Free Research Field

物性物理

Academic Significance and Societal Importance of the Research Achievements

多くの2:1塩および関連物質の中では比較的例の少ないフィリング制御型の金属ー絶縁体転移について、その分子価数の変化とともにフィリングが3/4からずれていても電荷秩序相転移が生じることを見いだした。これによって、有機分子性導体における電子相関による金属ー絶縁体転移の理解が一層深まったと考えられる。また、近年注目されているBEDT-TTF塩の薄膜系におけるキャリアドーピング効果などにも有益な情報となるだろう。